This project is concerned with the study of the molecular mechanisms of proacrosin conversion to acrosin; characterization of proacrosin and the conversion polypeptides in terms of amino acid composition, and groups, and carbohydrate content; the nature and mechanism of action of uterine fluid factors which stimulate proacrosin conversion to acrosin; the characteristics and mechanism of action of the sperm factor which inhibits this conversion; synthesis of other inhibitors; raising of antibodies to proacrosin on membrane bound proacrosin and the conversion peptides, and the study of their inhibitory activity on membrane bound proacrosin and their species cross-rectivity.